1. Field
The present disclosure relates generally to communication, and more specifically to techniques for sending messages with encoding.
2. Background
In a communication system, a transmitter may generate messages for information to be sent to a receiver. The transmitter may encode the messages to obtain codewords and further process the codewords to generate a modulated signal that is sent via a communication channel. The communication channel typically distorts the transmitted signal with a channel response and further degrades the signal with noise and interference. The receiver may receive the transmitted signal, process the received signal to obtain received codewords, decode the received codewords to obtain decoded messages, and extract the information from the decoded messages.
Encoding is typically performed in accordance with a particular coding scheme, which may include a block code, a convolutional code, a Turbo code, etc. The coding scheme may be selected based on a tradeoff between various factors such as error correction capability, amount of redundancy, decoding complexity, etc. In general, more redundancy results in longer codewords for a given message size but provides more error correction capability so that messages may be reliably sent in more degraded channel conditions. The converse is generally true for less redundancy.
A specific coding scheme may be selected based on pertinent factors. A codebook containing different codewords may be generated based on this coding scheme. Each message that might be sent may then be mapped to one specific codeword in the codebook, so that a one-to-one mapping exists between messages and codewords. This mapping may be determined by the manner in which the codewords are generated, e.g., each codeword may be generated based on an associated message. Furthermore, the mapping may be under an assumption that all messages are equally likely to be sent. Thus, the performance of the coding scheme is typically quantified by the worst codewords in the codebook.